Welder



FIG. 1 is a perspective view of a welder embodying the ornamental design of the present invention;

FIG. 2 is front view of the welder; and,

FIG. 3 is a head-on view of a control panel of the welder.

The broken lines in FIGS. 1-3 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a welder, as shown and described. 